Detachable drill bit



March 4Q 1941 QP. LIDDxcoA-r 2,233,421

DETACHABLE DRILL BI T Filed Oct. 5l, 1938 f/ @amv/W 32 ??Lzazyracm;

' JNVENTDR,

Traa/NER Patented Mar. 4, 1941 UNITED STATES PATENT olFFlcE DETACHABLEDRILL Brr Percill Liddicoat, St. Catharines, Ontario, Canada Applicationoctober s1, 193s, serial No. 2'37,s75 In Canada November 15, 1937 9Claims.

In the present invention I have devised a detachable drill bit withmodifications, adapted to be easily mounted, and di'smounted from thelend of the shank of a drill 'rod used in boring rock, ore, etc., inmining, and similar operations where boring is required through hardmaterial.

A feature of the invention is that the shank of the drill rod with whichthe bit is used may have any of the usual cross` sections, such assquare, 1'0 hexagonal, octagonal, oval or the like, and the lowerlextremity of the drill rod does not have or require any previously madespecial shape, or conformation in order to engage the bit, and .thesuccessive blows received by the drill rod in the l boring operation,are transmitted to the bit, and provide a method whereby the bit becomeslocked fast to the end of the drill rod. The bit in each of the formswhich are described herein; is provided with a socket or recess formedin the body of the bit, said socket having in turn small recesses,grooves, convolutions, corrugations and beveled surfaces formed therein,which are adapted to form on the end of the drill rod, complementaryprojections, shapes, and surfaces,

whichsecure the bit on the drill rod, as will be more fully described asthe description proceeds herein. Moreover the said projections, shapes,surfaces just mentioned are formed on the drill rod, by and during thevnormal operation of the drill rod, by means of the impacts received bythe drill rod from the machines and devices normally reciprocating, andtorsionally operating said rod. A

' The impacts received by the drill rod, being transmitted to the bit,directly over the cutting blades of the latter, tend to bore a `straighthole in the rock or other material being worked; and the torsion ofrotation of the drill rod is readily transmitted tothe flattened sidewalls of the bit socket, as will be fullydescribed below.

'I'he types of bit in 'the present invention can be easily and cheaplymanufactured by pressing or drop forging, without-subsequent machiningall of which tends to make the use of the bits in large numbers acommercial and practical matter.

This is an important consideration when it is stated that bits have tobe very frequently replaced on the drill rod, as they soon become dullon the cutting blades in service.

5o A most important feature is also the ease with which the bit can bedetached or dismounted from the drill rod shank, by merely hitting thebit on its outer perimeterl a few blows with a hammer, or the shank ofthe drill rod canreadily 5 be .withdrawn from the bit socket usingtools; in

which event it will be noted that the projections,

enlargements and the like which have 'been formed on the end of thedrill rod, are flattened sufficiently to permit the end o f thedrill rodto be re-inserted in other or freshly sharpened bits.

In the accompanying drawing forming part of this specification, I haveshown a physical embodiment of the invention, with .several modications,constructed according to the best mode I have so far devised for thepractical application 10 of the principles of my invention.

In said drawing, Figure 1 is a f ront elevation, partly in section, ofthe invention, showing a hexagonal shaped drill rod shank inserted inthe bit. i 15 Figure 2 is a top plan view of the bit shown f in Figure1.

Figure 3 is a side elevation of the device sho in Figure 1, taken fromthe position indicated in Figure 4; and with part of the device shown in20 section to show the interior of the bit.

Figure 4 is a bottom view of the bit shown in Figure 3.

Figure 6. Y Figure 8 is a plan view of another modification of the bit.l

Figure 9 is a front view in elevation of the Figure 8. 35

Figure 10 is a vertical section through a portion of a drill bit,illustrating a modied means of mounting a drill rod in the bit socket.-

Figure 11 is avertical section through a ,por-v tion of a drill Abit,illustrating another modified 40 means o'f mounting a drillrod in thesocketof the bit.

Figure 12 is an enlarged vertical -section through a portion of a drillbit illustrating in'detail the means for mounting the end of a vdrillrod in the 45 bit socket.

In the drawing, the numeral I indicates a rock cutting drill rod havingbefore its insertion in the socket of the bit 2, a plane fiat surface 3on its bottom end, and the side walls 4, l being fiat and forming thehexagonal sides of the rod as shown. The bit is provided with the usualcutting teeth, 5, 5, and is provided with the socket or recess 6, formedin cross-section complemen tary tothe drill rod.. At the bottom of therecess 6 are formed a series of smaller recesses 1, 1, etc., and thebottom I2 of the socket 'in this illustration is concave in shape. Onthe surface of this bottom are formed bossedV corrugations 9, 9, etc.,as clearly illustrated in Figures 1, 2 and 3 of the drawing. `It ispointed out that after the end of the drill rod is inserted in thesocket 6 of the bit, the repeated blows on the upper end of the drillrod, drive the rod downward into the bottom of the socket, and the metalof the rod shank 8 forms protrusions or projections I0, I0 thereon, andthe metal of the bottom of the drill rod also forms complementary shapesto the convolutions or corrugations 9, 9, the metal being crowdedsomewhat between each pair of same as is at once understood. The beveledor concaved surface I2, on whichA the corrugations 9, 9 are formed asmay be readily understood from Figure 12 tends to form the projectionsI0, I0 on the end of the drill rod. 'I'here is no objection however sofar as the formation -of the projections I0, I are concerned to havingthe bottom of the recess 6 fiat as at I3, in Figure 10. In the type ofthe device just -described in reference to Figures 1 to 4 inclusive itis evident that the drill rod I, when itis withdrawn from the bit 2 hasthe projections I0, I0, etc., flattened out in line with the surface ofthe side walls of the drill rod, so that the drill rod can readily beused for reinsertion in any other bit, or in the old one after thecutting blades have been re-sharpened for subsequent use.

While in the type of bit and drill rod just described the cross-sectionof the drill rod is hexagonal, it is evident that any other type ofcross-section commonly used, such as a square,

oval, or hexagonal cross-section may be used, if the socket of the bitis made complementary thereto.

In the Figures 5, 6-and 7 of the drawing is shown a modified form of theinvention, in which the drill rod is of the. square type, and acontinuous groove I4-is formed at the base of the socket or recess I5 ofthe bit I6. It is evident that the drill rod I1 may be Withdrawn fromthe bit in the same way as before described, and the projection I8 inlthe groove I4 flattened-out in the same manner as the projections I0,I0 of Figure 1. In some cases the bit may be provided with a centralhole or passage. I9, which permits water to pass through the bit, andalso is of assistance in removing the rod from the bit. This is true ofall the types of bit mentioned in this specification.

In the Figures 8 and 9 of the drawing is shown another modified form ofbit, which is provided with recesses 20, 20, etc., formed in the sidewalls of the socket 2|', and between the corners22, 22, of the socket 2I. These various types of recesses, such as 1, 1, and corrugations 9, 9concaved bottom I2, shown in Figures 1, 2 and 3; the groove I4, Figure5; and the small recesses 20, 20 of Figures 8 and 9; may all be used incombination as desired, and as found suitable to the particularcross-sectional shape of the drill rod being used.

In the Figures 10, 11 and 12 is illustrated diagrammatically severalfeatures of the invention,

drill rod and the walls of th socket. In other instances it may be founddesirable to have the walls of the socket of the bit tapered slightly asillustrated at 21, Figure 11 of the drawing. Moreover this type ofbeveled or tapered side walls may be used with or without the driven tor binding action just described between the drill rod and the socketwalls. In some instances the top edges of the sockets of the bits mayhave a beveled or flared mouth as at 28, 28 to permit of easy insertionof the drill rod, asis at once undery stood. Also in some cases it maybe deemed advantageous to bevel the exterior top edges of the bit asshown at 29 Figure 1, or 30 in Figure 9.

In Figure 12 the advantage of having a concaved bottom I2 for the bitrecess, or a beveled partially cone-shaped bottom, is clearlyillustrated, as it is at once evident from this enlarged drawingthatwhen the drill rod shank 3I meets the beveled or curved surface I2,at points 32, 32, there is a tendency to cause the material of theshank' to at once form the desired projecting bosses I0, I0 which arethus formed complementary in shape to the recesses 1, 1 and form themeans of locking the bit on the end of the drill rod; and also toconform the said material to the corrugations 9, 9.

Referring now to the features and advantages mentioned in the preambleof this specification, it is believed after what has been described,that these features are readily understood. Itis especially emphasizedthat in the present invention, no unusual preparation is needed for theshank of the drill rod, when the present type of drill bit is used; inother words the end and the sides ofthe shank of the drill rod are planesurfaces in correspondence lwith the type of crosssection of the rodbeing used, square, hexagonal, oval, etc., being used. In many of thedrill bit devices in current use the end of the drill shank has toreceive considerable preliminary treatment, in order to be used with aspecial type of bit. In the present device it is evident no preliminarytreatment or manipulation lwhatever is required for the end of the saidrod other than the use of a cross-sectional shape ofv rod correspondingto the type of socket in the drill bit. Moreover the same shank maybeused many times, after withdrawal from-the bit.

Attention is called to the ease with which the bit is secured on thedrill rod, by means of the first few impacts received by the drill rodduring its ordinary reciprocation in service. Also'how easily the bitmay be again detached vfrom the shank of the drill rod for replacementpurposes. This last feature is of course one of the important featuresof the invention, since bits have to be replaced frequently in miningand similar boring operations, as is at once understood.

As the bits have to be rotated torsionally when in use, the torsionalrotation is transferred from the ydrill rod to the bit by means of theshaped sidewalls of the rod and the bit socket.

By means of the bit undercut recesses, depressions, grooves andcorrugated surfaces the necesl sary enlargements, bosses, projectionsand conformations are readily formed on the end of the rod shank, andyetthese deformations are such that the end of the same may readily bewithdrawn from the bit, ready for a subsequent use, and for a largenumber of repetitions of such use.

From which description, as above given, it' is seen that I have providedan exceptionally useful type of detachable drill bit device, which isnot lexpensive to manufacture, which requiresv no drill rod ofsubstantially angular cross-section, a bit with a socket ofcomplementary outline to that of the rod, having a number of undercutrecesses formed therein between the angular corners of the socket, and ayielding end on the drill rod adapted to engage the undercut recessesand form a holding means for the bit, when the 'drill rod isreciprocated during the drilling operation, and said rod also beingadapted to be readily detached from the bit, when itis necessary toplace a resharpened or a'new bit on the end of the rod.

2, A drill rod and bit assembly for percussive drilling, said assemblyconsisting of a bit having cutting teeth lon its lower portion andhaving its -upper portion shaped to dene a central recess,

open at its upper end and bounded by an upstanding annular Wall and abottom seat, said wall'having a side recess on its inner face positionedclose to said seat, and a drill rod slidably entered in said bit andwith an end engaging said seat, said end being formed of a materialintegral with the rod and arranged deformable upon impact of the end onthe seat when the assembly is used in cutting to provide an end edgeportion movable into said side recess to hold the rod and bit inassembled relation during the cutting operation, said end edge portionbeing arranged readily deformable toA facilitate the withdrawal of therod from the bit at the end of a cutting operation.

3. A drill rod and bitv assembly for percussive drilling, said assemblyconsisting of a bit having cutting teeth on its lower portion and havingits upper por-tion shaped to dene a centralv recess open at its upperend and bounded by an upstanding annular wall and a concave bottom seat,said wall having a side recess on its inner face positioned close tosaid seat, and a drill rod slidably entered in said bit with its lowerend having a marginal portion seated on said-seat, said end being of amaterial arranged deformable upon impact of the end on the seat' whenthe assembly is used in ycutting to providean end edge portion movableinto said side recess to hold the rod and bit in assembled relationduring the cutting operation. Y

4. A drill rod and bit assembly for percussive drilling, said asssemblyconsisting of a bit having cutting teeth on its lower portion and havingits upper -portion shaped to deiine a central recess open at its upperend and bounded by an upstanding annular wall and a bottom seat, saidseat being shaped to dene a plurality of upstanding and spaced anvils,said wall having a side recess on its inner face and close to said seat,a drill rod slidably entered in said bit with its lower end engagingsaid anvils, said end being of a material arranged workable upon saidanvils upon impact of said end on said anvils when the assembly is usedinA cutting to provide an end edge portion movable into said side recessand a face portion tting between said anvils.

5. A drill rod and bit assemblyfor percussive drilling, said`assemblycomprising a bit having cutting teeth on its lower portion and havingits upper portion shaped to define a central recess open at its upperend and bounded by an upstanding annular wall and a bottom seat, saidwall having a side recess on its inner face positioned close to saidseat, means on said seat deining a plurality of spaced anvils eachhaving a curved upper face adapted to engage the bottom end of a drillrod entered in said recess, a drill rod slidably entered in said bit andwith its bottom end seated on said anvils, said end being of a materialdeformable upon. impact of said end on said anvils when the assembly isused in cutting to provide an end edge portion movable into said siderecess to hold the rod and bit in assembled .relation during a cuttingoperation, said end being also deformable to lit between said anvils andresist relative turning of said rod and bit.

6. A drill bit having cutting teeth on its lower portion and having itsupper portion shaped to define a central recess open at its upper endand bounded by an upstanding annular wall and a bottom seat, said seatbeing shaped to define a plurality of spaced and upstanding anvils, and

said wall being provided with a side recess on its inner face andpositioned close to said seat. 7. A drill bit having cutting teeth onitslower portion and having its upper portion shaped to deiine a centralrecess open at its upper end and bounded by an upstanding annular walland a concave bottom seat, said wall having a single groove only whichis positioned close to said seat.

8. A drill rod and bit assembly for percussive drilling, said assemblycomprising a bit having a central recess bounded by an upstandingannular wall and a bottom s'eat, a drill rod slidably entered in saidrecess and having an end seated on said seat, means operable upon impactof said end on said seatv when the assembly is used in cutting toremovably connect said bit and said rod in assembled relation, saidmeans comprising a groove formed on the inner face of said wall andclose to said seat and integrally formed vmetal at the end of said rodarranged deform- 9. A drill rod and bit assembly for percussivedrilling, said assembly `comprising a drill rod and a bit adapted tohouse an end of said rod, means in said bit defining a seat forthe-housed end of the rod, said rod being freely slidable in said bit toengage said seat until said end of the rod is deformed by impact on saidseat when the assembly is used in cutting, said end-of said rod beingformed of material integral with said rod and deformable under impact,and means in said bit normally out of engagement with said rod andcooperable with said end of said rod when the assembly is used incutting to engage said end 'and hold said bit and said rod in assembledrelation.

` PERCILL LIDDICOAT.

